REF: remove Index._convert_arr_indexer (pandas-dev#41884)

Author: jbrockmendel

pandas/core/indexes/base.py

@@ -3664,43 +3664,6 @@ def is_int(v):
 
         return indexer
 
-    def _convert_listlike_indexer(self, keyarr):
-        """
-        Parameters
-        ----------
-        keyarr : list-like
-            Indexer to convert.
-
-        Returns
-        -------
-        indexer : numpy.ndarray or None
-            Return an ndarray or None if cannot convert.
-        keyarr : numpy.ndarray
-            Return tuple-safe keys.
-        """
-        if isinstance(keyarr, Index):
-            pass
-        else:
-            keyarr = self._convert_arr_indexer(keyarr)
-
-        indexer = None
-        return indexer, keyarr
-
-    def _convert_arr_indexer(self, keyarr) -> np.ndarray:
-        """
-        Convert an array-like indexer to the appropriate dtype.
-
-        Parameters
-        ----------
-        keyarr : array-like
-            Indexer to convert.
-
-        Returns
-        -------
-        converted_keyarr : array-like
-        """
-        return com.asarray_tuplesafe(keyarr)
-
     @final
     def _invalid_indexer(self, form: str_t, key) -> TypeError:
         """

pandas/core/indexes/multi.py

@@ -2581,29 +2581,29 @@ def _get_values_for_loc(self, series: Series, loc, key):
         new_ser = series._constructor(new_values, index=new_index, name=series.name)
         return new_ser.__finalize__(series)
 
-    def _convert_listlike_indexer(self, keyarr):
+    def _convert_listlike_indexer(self, keyarr) -> np.ndarray | None:
         """
+        Analogous to get_indexer when we are partial-indexing on our first level.
+
         Parameters
         ----------
-        keyarr : list-like
+        keyarr : Index, np.ndarray, or ExtensionArray
             Indexer to convert.
 
         Returns
         -------
-        tuple (indexer, keyarr)
-            indexer is an ndarray or None if cannot convert
-            keyarr are tuple-safe keys
+        np.ndarray[intp] or None
         """
-        indexer, keyarr = super()._convert_listlike_indexer(keyarr)
+        indexer = None
 
         # are we indexing a specific level
-        if indexer is None and len(keyarr) and not isinstance(keyarr[0], tuple):
-            level = 0
-            _, indexer = self.reindex(keyarr, level=level)
+        if len(keyarr) and not isinstance(keyarr[0], tuple):
+            _, indexer = self.reindex(keyarr, level=0)
 
             # take all
             if indexer is None:
-                indexer = np.arange(len(self))
+                indexer = np.arange(len(self), dtype=np.intp)
+                return indexer
 
             check = self.levels[0].get_indexer(keyarr)
             mask = check == -1
@@ -2614,7 +2614,7 @@ def _convert_listlike_indexer(self, keyarr):
                 # actually in Index anymore
                 raise KeyError(f"{keyarr} not in index")
 
-        return indexer, keyarr
+        return indexer
 
     def _get_partial_string_timestamp_match_key(self, key):
         """

pandas/core/indexing.py

@@ -1286,13 +1286,21 @@ def _get_listlike_indexer(self, key, axis: int):
         """
         ax = self.obj._get_axis(axis)
 
-        # Have the index compute an indexer or return None
-        # if it cannot handle:
-        indexer, keyarr = ax._convert_listlike_indexer(key)
-        # We only act on all found values:
-        if indexer is not None and (indexer != -1).all():
-            # _validate_read_indexer is a no-op if no -1s, so skip
-            return ax[indexer], indexer
+        keyarr = key
+        if not isinstance(keyarr, Index):
+            keyarr = com.asarray_tuplesafe(keyarr)
+
+        if isinstance(ax, MultiIndex):
+            # get_indexer expects a MultiIndex or sequence of tuples, but
+            #  we may be doing partial-indexing, so need an extra check
+
+            # Have the index compute an indexer or return None
+            # if it cannot handle:
+            indexer = ax._convert_listlike_indexer(keyarr)
+            # We only act on all found values:
+            if indexer is not None and (indexer != -1).all():
+                # _validate_read_indexer is a no-op if no -1s, so skip
+                return ax[indexer], indexer
 
         if ax._index_as_unique:
             indexer = ax.get_indexer_for(keyarr)